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#include <iostream>
#include <array>
constexpr int MAX_N = 100000;

void peekUntillTowns() {
	char c = std::cin.peek();
	while (c != '1' && c != '0') {
		getchar();
		c = std::cin.peek();
	}
}

int towns[MAX_N];
int n = 0;

int firstStreak = 0;
int lastStreak = 0;
bool areAnyTownsSick = false;

int highestStreak = 0;

bool areThereCitiesToRescue(const int& streakLength, const int& turnsPassed) {
	return streakLength - 2 * turnsPassed > 0;
}

bool shouldRescueOneWayStreak(const int& oneWayStreakCurrentLength, const int& currentLength) {
	return oneWayStreakCurrentLength > currentLength / 2;
}

bool shouldRescueFirstStreak(const int& firstStreakCurrentLength, const int& lastStreakCurrentLength, const int& currentLength) {
	return firstStreakCurrentLength > currentLength / 2 && firstStreakCurrentLength >= lastStreakCurrentLength;
}

bool shouldRescueLastStreak(const int& firstStreakCurrentLength, const int& lastStreakCurrentLength, const int& currentLength) {
	return lastStreakCurrentLength > currentLength / 2 && lastStreakCurrentLength >= firstStreakCurrentLength;
}

int solveOne() {
	// reset variables
	for (int i = highestStreak; i >= 0; i--)
		towns[i] = 0;
	n = 0;
	firstStreak = 0;
	lastStreak = 0;
	areAnyTownsSick = false;
	highestStreak = 0;

	// start parsing
	std::cin >> n;
	peekUntillTowns();

	int currentTownStreak = 0;
	bool isFirstStreakRead = false;

	for (int i = 0; i < n; i++) {
		char c = getchar();
		if (c == '0') {
			currentTownStreak++;
			if (i == n - 1) {
				lastStreak = currentTownStreak;
			}
		}
		else {
			areAnyTownsSick = true;
			if (!isFirstStreakRead) {
				firstStreak = currentTownStreak;
				isFirstStreakRead = true;
			}
			else {
				towns[currentTownStreak]++;
				if (highestStreak < currentTownStreak)
					highestStreak = currentTownStreak;
			}
			currentTownStreak = 0;
		}
	}
	// everything parsed

	// no sick towns case
	if (!areAnyTownsSick) {
		return 0;
	}

	int rescuedTowns = 0;
	int turnsPassed = 0;

	int i = highestStreak;
	while (i > 0) {
		if (!areThereCitiesToRescue(i, turnsPassed))
			break;
		int townStreaksWithLengthI = towns[i];
		if (townStreaksWithLengthI <= 0) {
			i--;
			continue;
		}

		int currentLength = i - 2 * turnsPassed;
		if (shouldRescueFirstStreak(firstStreak - turnsPassed, lastStreak - turnsPassed, currentLength)) {
			rescuedTowns += firstStreak - turnsPassed;
			firstStreak = 0;
			turnsPassed += 1;
			continue;
		}

		if (shouldRescueLastStreak(firstStreak - turnsPassed, lastStreak - turnsPassed, currentLength)) {
			rescuedTowns += lastStreak - turnsPassed;
			lastStreak = 0;
			turnsPassed += 1;
			continue;
		}

		if (currentLength <= 2) {
			rescuedTowns += 1;
			turnsPassed += 1;
		}
		else {
			rescuedTowns += currentLength - 1;
			turnsPassed += 2;
		}
		towns[i]--;
	}
	// bidirectional calculated

	if (firstStreak - turnsPassed > 0) {
		rescuedTowns += firstStreak - turnsPassed;
		turnsPassed += 1;
	}
	if (lastStreak - turnsPassed > 0) {
		rescuedTowns += lastStreak - turnsPassed;
		turnsPassed += 1;
	}

	return n - rescuedTowns;
}

void solveAll() {
	int t = 0;;
	int result = 0;
	std::cin >> t;
	for (int i = 0; i < t; i++) {
		std::cout << solveOne();
		if (i < t - 1)
			std::cout << std::endl;
	}
}

int main() {
	solveAll();
}